Steer axle high-temperature warning system

ABSTRACT

A high temperature warning system for a vehicle steer axle an air pressure supply, a normally-closed valve in fluid communication with pressure supply, a heat sensitive control capable of opening the normally-closed valve upon a predetermined temperature, the heat sensitive control mounted adjacent to the wheel end assembly in a heat exchange relationship therewith, and a warning system connected to the air pressure supply for actuation upon opening of the normally-closed valve.

CROSS-REFERENCE TO RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.14/536,326 filed Nov. 7, 2014, which is a continuation of U.S. patentapplication Ser. No. 13/808,940 filed Apr. 23, 2013, which issued asU.S. Pat. No. 8,910,683 on Dec. 16, 2014, which claims priority of PCTPatent Application No. PCT/US2011/044879 filed on Jul. 21, 2011, whichclaims priority to U.S. Provisional Patent Application No. 61/368,960entitled “Steer-Axle High-Temperature Warning System” filed Jul. 29,2010, all of which are hereby incorporated in their entirety byreference.

FIELD

The disclosed system relates generally to high temperature warningsystems for vehicle steer axles.

BACKGROUND

In the event of a failure associated with the wheel end, such as abearing failure or brake failure, elements of the wheel end can heat upand reach high temperatures very quickly. When these high temperaturesare reached by the wheel end, tires and/or lubricant may ignite andcause the wheel to lock up or the vehicle to burn. Due to the intenseheat caused by a wheel end failure, it is also possible that the wheelcan detach from the axle.

SUMMARY

A high temperature warning system for a steer-axle wheel end assembly,the system comprising: an air pressure supply, a normally-closed valvein sealed fluid communication with the air pressure supply, a heatsensitive control capable of opening the normally-closed valve upon apredetermined temperature, the heat sensitive control mounted on or nearthe steer-axle wheel end assembly in a heat exchange relationshiptherewith, and a warning indicator connected to the air pressure supplyfor actuation upon opening of the normally-closed valve.

An automatic tire inflation and high-temperature warning system for asteer-axle wheel end assembly comprising a spindle, bearings mounted tothe spindle, a hub rotatably mounted to the bearings, a wheel mounted tothe hub, and a pneumatic tire mounted to the wheel, the systemcomprising: an air pressure supply, a rotary union mounted to thespindle and in sealed communication with the air pressure supply andwith the tire, a normally-closed valve in sealed fluid communicationwith the air pressure supply, a heat sensitive control capable ofopening the normally-closed valve upon a predetermined temperature, theheat sensitive control mounted on or near the steer-axle wheel endassembly in a heat exchange relationship therewith, and a warningindicator connected to the air pressure supply for actuation uponopening of the normally-closed valve.

A high temperature warning system for a steer-axle wheel end assembly,the system comprising: a normally-closed valve capable of sealed fluidcommunication with an air pressure supply, a heat sensitive controlmountable on or near the steer-axle wheel end assembly in a heatexchange relationship therewith, and capable of connecting to thenormally-closed valve and opening the normally-closed valve upon apredetermined temperature, and warning indicator connected to the airpressure supply for actuation upon opening of the normally-closed valve.

A high temperature warning system for a steer-axle wheel end assembly,the system comprising: an air pressure supply, a electrically-operatednormally-closed valve in sealed fluid communication with the airpressure supply, a thermal electric switch capable of opening thenormally-closed valve upon a predetermined temperature, the thermalelectric switch mounted on or near the steer-axle wheel end assembly ina heat exchange relationship therewith, and a warning indicatorconnected to the air pressure supply for actuation upon opening of theelectrically-operated normally-closed valve.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates one embodiment of a vehicle that may use a steer-axlehigh-temperature warning system.

FIG. 2. illustrates an exploded view of one embodiment of a steer-axlehigh-temperature warning system.

FIG. 3 illustrates a cut-away view of one embodiment of a wheel spindle.

FIG. 4 illustrates a cut-away side view of one embodiment of asteer-axle high-temperature warning system.

FIG. 5 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 6 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 7 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 8 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 9 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 10 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 11 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 12 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 13 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 14 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 15 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system.

FIG. 16 illustrates a partially exploded view of one embodiment of asteer-axle high-temperature warning system with an automatic tireinflation system.

FIG. 17 illustrates a cut-away side view of another embodiment of asteer-axle high-temperature warning system with an automatic tireinflation system.

FIG. 18 illustrates a cut-away, side view of another embodiment of asteer-axle high-temperature warning system with an automatic tireinflation system.

FIG. 19 illustrates a cut-away, side view of another embodiment of asteer-axle high-temperature warning system with an automatic tireinflation system.

DETAILED DESCRIPTION

As may be seen in FIG. 1, a vehicle 100 may comprise a truck 102 andtrailer 104. The truck 102 may include one or more drive axles 106 aspart of the vehicle's powertrain. The truck 102 may further include asteer axle 114 having pivoting hubs that provide steering capability forthe vehicle 100. The trailer 104 may include one or more fixed axles(not shown). Each axle may have one or more wheels 108 mounted theretowith a tire 110 mounted to each wheel 108. Of course, other types ofsteerable vehicles, such as cars and buses may be provided with the hightemperature warning system disclosed herein.

The vehicle 100 may be provided with a pressurized air supply (notshown) used to provide pressurized air to brakes (not shown) and/or toan automatic tire inflation system (indicated with air hoses 112). Thesteer-axle high-temperature warning system (shown in more detail inFIGS. 4-19) may warn a driver when the steer axle 114 and/or steer axlewheel end reach a predetermined temperature.

Referring now primarily to FIG. 2, a vehicle may include a wheel-endhigh-temperature warning system 150 and a steer axle 114 having a wheelspindle 154 on which a wheel end assembly 156 may be mounted. The wheelend assembly 156 may include a hub (not shown) which may rotate on innerbearings 158 and outer bearings 178. A wheel 108, tire 110 (as shown inFIG. 1) and hubcap may be mounted to the hub. A brake drum (not shown)may be integrally formed with the hub, or otherwise mounted to the hub.The wheel end assembly 156 may also include other suitable parts whichare not shown but may be monitored by the wheel-end high-temperaturewarning system 150.

The outer bearings 178 may be retained on the wheel spindle 154 by aspindle nut 160. A washer 162 may be mounted between the spindle nut 160and outer bearing 178. A cotter pin 164 may be inserted through areceiving hole 166 in the end of the wheel spindle 154 so as to preventthe spindle nut 160 from becoming unscrewed from the wheel spindle 154.The wheel spindle 154 may be pivotally mounted to the front steer axle114 via a knuckle post assembly (not shown).

An oil seal 168 may be mounted to the wheel spindle 154 adjacent theinner bearing 158 so as to prevent loss of lubricant through the innerbearing 158. A hub cap 606 (as shown in FIGS. 16-19) may be mounted tothe hub, thus generally sealing the bearings 158 and 178 from debris andpreventing loss of lubrication.

If the bearings 158 and 178, brakes, or other elements of the wheel endfail, the temperature in the bearings 158 and 178, brake drum, wheelspindle 154, or other wheel end elements may reach in a temperature highenough to ignite the tires 110 and bearing lubricant. Such heat may alsobe sufficiently high to cause the wheel end assembly 156 to detach fromthe wheel spindle 154. The disclosed high-temperature warning system maywarn the vehicle operator of high temperatures well before the tiresignite or bearings melt, or some other dangerous high-temperaturerelated condition arises in the wheel-end.

The high-temperature warning system 150 may include an air pressuresupply 152, such as that typically provided on a truck 102 or vehicle100 for various purposes such as air brakes; a pressure protection valve170; a flow switch 172; and an indicator or warning system light 174. Anair conduit 176 may connect the air pressure supply 152 to one or morenormally-closed valves 256 (as shown in the embodiments of FIGS. 4-19).

FIG. 3 shows a cross section of the exemplary wheel spindle 154 of FIG.2. As may be seen in FIG. 4, the air conduit 176 may be connected to avalve block 252 mounted to the inner face 254 of the wheel spindle 154.In some embodiments, the valve block 252 may be comprised of metal orany other suitable thermally-conductive material, and may mounted to thewheel spindle 154, such as by threadable attachment. The valve block 252may be suitably configured so as to allow the valve block 252 to remainat or near the temperature of the wheel spindle 154 when mountedthereto. A normally-closed valve 256 may be mounted to the valve block252 in fluid communication with the air conduit 176 through a channel262 which connects the air conduit 176 with the normally-closed valve256.

The normally-closed valve 256 may be opened by a heat sensitive control.In one embodiment, the heat sensitive control may be configured todetect temperature and to open the normally-closed valve 256 when apredetermined temperature is measured. A pre-determined temperature maybe, for example, a temperature well below the softening or melting pointof the bearing materials, or well below the tire melting point. Thepre-determined temperature may be set well above the maximumtemperatures at which a wheel-end assembly may normally operate so as toavoid false alarms. Thus, when the temperature near the hear sensitivecontrol reaches the predetermined temperature, the heat sensitivecontrol will open the normally-closed valve 256 to allow air to passthrough the normally-closed valve 256.

The heat sensitive control may be any device which is capable ofdetecting temperature and either directly or indirectly opening anormally-closed valve in response thereto. For example, in someembodiments, the heat sensitive control is fusible plug 258, a thermallyelectric switch 552, or any other suitable control. The normally-closedvalve 256 and the heat sensitive control may be located at separatelocations on the vehicle 100. The heat sensitive control may be mountedin or near the wheel-end assembly in a heat-exchange relationshiptherewith. In some embodiments the heat sensitive control may be in aconductive heat exchange relationship with the wheel end assembly suchthat the heat sensitive control detects the approximate temperature ofwheel end assembly or specific components thereof, such as the bearingsor brakes. For example, the heat sensitive control may be mounted nearthe wheel end assembly 156 while the normally-closed valve 256 ismounted at or near the air pressure supply 152. In other embodiments,the heat sensitive control may be mounted near the wheel end assembly156 while the normally-closed valve 256 is mounted at another point onor near the wheel end assembly 156, for example as shown in FIGS. 10-15and 19. In other embodiments, the heat sensitive control may be includedwithin the normally-closed valve 256 and both the heat sensitive controland the normally-closed valve 256 may be located at the same position ator near the wheel end assembly 156. For example, in the embodiments ofFIGS. 4-9 and 17-18, the heat sensitive control is contained within thenormally-closed valve 256. In FIGS. 4-9 and 17-18, the heat sensitivecontrol is a fusible plug 258 comprising of a eutectic alloy. In oneembodiment, the fusible plug 258 is placed within an aperture 260 withinthe normally-closed valve 256. The fusible plug 258 may seal theaperture 260 by being located within the aperture 260, as shown in FIG.4. The fusible plug 258 may open the normally-closed valve 256 upon apredetermined temperature by melting sharply at the predeterminedtemperature and thus un-sealing the aperture 260 in the normally-closedvalve 256. Thus, the fusible plug 258 may be automatically removed fromthe aperture 260 when the predetermined temperature is reached, thusopening the normally-closed valve 256. While any type of fusible plug258 may be satisfactorily used, one sold under the trademark LEEKPRUFsold by the Mueller Refrigeration Company, Inc., is suitable. In someembodiments, when the eutectic alloy of the fusible plug 258 melts, airmay escape from the air pressure supply 152 through the normally-closedvalve 256 via air conduct 176. The escaping air may be detected by theflow switch 172, which may actuate the warning system light 174 showingFIG. 1. The warning system light 174 may be positioned within view ofthe driver of the vehicle 100 to indicate a problem. In otherembodiments, air may escape when the normally-closed valve 256 isautomatically opened, for example, by a thermal electric switch.

As may be seen in the embodiments of FIGS. 5-19, one or morenormally-closed valves 256 may be provided in various combinations andat various exemplary locations. Other types of thermally operated,normally-closed valves 256 and heat sensitive controls may also be used.For example, the heat sensitive control may be a thermal electric switch552 which actuates an electrically-operated normally-closed valve 256upon a predetermined temperature, as shown in FIGS. 10-15 and 19. Thethermal electric switch 552 may actuate the electrically-operatednormally-closed valve 256 by sending an electric signal via wire orwirelessly to the electrically-operated normally-closed valve 256 whenthe thermal electric switch 552 reaches a predetermined temperature. Theelectrically-operated normally-closed valve 256 may then receive thesignal and open the normally-closed valve 256. Thus, in someembodiments, the normally-closed valve 256 includes the heat sensitivecontrol 57 (as shown in FIGS. 4-9 and 16-18) while in other embodiments,the heat sensitive control 57 may be located remotely from thenormally-closed valve 256 and may communicate (electronically orotherwise) with and open the normally-closed valve 256 (as shown inFIGS. 10-15 and 19).

In the embodiment of FIG. 5, the wheel spindle 154 may be bored alongits central axis to provide an axial channel 302 in fluid communicationwith the air conduit 176. A normally-closed valve 256 containing theheat sensitive control, in this embodiment a fusible plug 258 comprisinga eutectic alloy, may be threadably mounted in the axial channel 302 atthe outer end of the spindle 154. The air conduit 176 may be sealinglyconnected to the axial channel 302 at the inner face 254 of the spindle154, or may extend through the axial channel 302 and sealingly connectto the normally-closed valve 256. In some embodiments, when the wheelspindle 154 or surrounding wheel end assembly 156 elements reach apredetermined temperature, the eutectic alloy may melt and open theaperture 260 in the normally-closed valve 256 such that air from the airconduit 176 flows through the aperture 260. A pre-determined temperaturemay be, for example, a temperature substantially below the temperatureat which bearing lubricant burns or bearings melt.

In the embodiment of FIG. 6, a radial channel 352 may extend from theaxial channel 302 to an external surface of the spindle 154 so as toallow mounting of a normally-closed valve 256 adjacent the innerbearings 158 and/or outer bearings 178 (shown in FIG. 2). Thenormally-closed valve 256 may be sealingly mounted in the radial channel256 at the external surface of the spindle so as to be in fluidcommunication with the air conduit 176 such that when thenormally-closed valve 256 is opened, air from the air conduit 176 canescape through the normally-closed valve 256. As shown in the embodimentof FIG. 6, the air conduit 176 may be sealingly connected from the airpressure supply 152 to the inner face 254 of the wheel spindle 154 so asto supply pressurized air to a normally-closed valve 256 without needfor a valve block 252. In some embodiments, the air conduit 176 may beinserted through the axial channel 302 and/or radial channel 352 tosealingly connect with the normally-closed valve 256 so as to allowsealed fluid communication from the air pressure supply 152 to thenormally-closed valve 256.

In the embodiment of FIG. 7, normally-closed valves 256 may be locatedat one end 303 of the axial channel 302 and in the radial channel 352.The embodiment of FIG. 7 may not include a valve block 252 but ratherthe air conduit 176 may sealingly connect to the axial channel 302. Ofcourse, the air conduit 176 may also extend through the axial and radialchannels for sealing connection directly with the normally-closedvalves. In this embodiment, the heat sensitive control 258 may becontained within the normally-closed valve 256 and may comprise afusible plug 258 made of a eutectic alloy.

In the embodiment of FIG. 8, the air conduit 176 may sealingly connectwith the valve block 252. Normally-closed valves 256 may be located atone end 303 of the axial channel 302 and in valve block 252. The valveblock 252 may include channels 262 which allow the air conduit 176 tofluid communication with the axial channel 302 and the normally-closedvalves 256. In this embodiment, the heat sensitive control 258 may becontained within the normally-closed valve 256 and may comprise afusible plug 258 made of a eutectic alloy.

In the embodiment of FIG. 9, normally-closed valves 256 may be mountedin the radial channel 352 in the valve block 252. In this embodiment,the heat sensitive control 258 may be contained within thenormally-closed valve 256 and may comprise a fusible plug 258 made of aeutectic alloy.

In some embodiments, the air conduit 176 may sealingly connect the airpressure supply 152 to the valve block 252 (as shown in FIG. 9) or axialchannel 302 of the wheel spindle 154 (as shown in FIGS. 5-7). In someembodiments, the air conduit 176 may run through a hollow front steeraxle 114. In some embodiments, the air conduit 176 may run alongside thefront steer axle 114. In some embodiments, the hollow front steer axle114 may be bored or plugged at each end (not shown), and the air conduit176 may be connected to the hollow front steer axle 114 so as to use thehollow front steer axle 114 as part of the air conduit or pressuresupply. An air line (not shown) may extend from an axle plug (not shown)to the valve block 252 or inner face 254 of the wheel spindle 154 toprovide fluid communication between the air pressure supply 152 and thenormally-closed valves 256.

Referring now to FIGS. 10-15, the heat sensitive control may be athermal electric switch 552 which operates an electric-operatednormally-closed valve 554 mounted in a valve block 252 similarly to thevalves of previous embodiments. The thermal electric switch 552 and theelectric-operated normally-closed valve 554 may each include a powersource, may receive power from an external power source or may not needa power source. In the embodiment of FIG. 10, thermally electricswitches 552 may be mounted at a variety of locations at or near thewheel end assembly 156. For example, a thermally electric switch 552 maybe located at the end of the wheel spindle 154. Other thermally electricswitches 552 may be located on an inner face 254 of the wheel spindle154. Yet another thermal electric switch 552 may be located on the steeraxle 114. Each thermal electric switch 552 may communicate with thenormally-closed valve 256 which may be an electric-operatednormally-closed valve 554. In some embodiments, when any one of thethermally electric switches 552 reaches a predetermined temperature, itwill send a signal to the electric-operated normally-closed valve 554 tocause the electric-operated normally-closed valve 554 to open. In otherembodiments, the thermally electric switches 552 may communicate witheach other or a central processing unit, and may be configured tocommunicate with the electric-operated normally-closed valve 554 when acertain number of thermal electric switches 552 have reached apredetermined temperature.

The embodiment of FIG. 11 includes one electric-operated normally-closedvalve 554 which is located in the axial channel 302 and a thermalelectric switch 552 which is located on the inner face 254 of the wheelspindle 154. The embodiment of FIG. 12 includes one electric-operatednormally-closed valve 554 which is located in the radial channel 352 andone thermal electric switch 552 which is located on the wheel spindle154. The embodiment of FIG. 13 includes two thermally electric switches552 which are located on the inner face 254 of the wheel spindle 154 andone electric-operated normally-closed valve 554 is located in the axialchannel 302. The embodiment of FIG. 13 also includes one normally-closedvalve 256 including a fusible plug 258 made of a eutectic alloy which islocated in the radial channel 352. The embodiment of FIG. 14 includestwo electric-operated normally-closed valves 554 and twoelectric-operated normally-closed valves 554, one which is located inthe axial channel 302 and one which is located on the steer axle 114.The embodiment of FIG. 15 includes two thermally electric switches 552,one which is located in the radial channel 352 and one which is locatedin the valve block 252, and one thermally electric switch 552 which islocated on the valve block 252.

Of course, the number and locations of thermal electric switches 552 inthe foregoing embodiment should not be viewed as limiting. Otherembodiments may include fewer or additional thermally electric switchesand normally-closed valves in a variety of other locations in and aboutthe wheel end assembly. Likewise, thermally-operated normally-closedvalves may be used in combination with fusible plug normally-closedvalves. The valve block 252 may be of any suitable configuration adaptedfor mounting to the wheel spindle, whether at the inner face 254 orelsewhere. The valve block 252 may be further provided with one or morechannels 262 to allow fluid communication from air conduit 176 to one ormore normally-closed valves. Furthermore, the radial channel 352 mayextend from the axial channel 302 at any point along the axial channel302. A wheel spindle may have formed therein more than one axial channel302 and may have formed therein more than one radial channel 352.

The high temperature warning system may provide a stand-alone system forvehicles, or the warning system may be easily adapted for use with anautomatic tire inflation system which may also use the air pressuresupply 152 and a warning system light 174 shown in FIG. 1. The hightemperature warning system may be used with various types of automatictire inflation systems, one type of which is shown in the embodiments ofFIGS. 16-19 and more fully described and illustrated in U.S. Pat. No.6,698,482, entitled “Rotary Air Connection With Bearing For TireInflation System,” which is hereby incorporated by reference. As shownin FIG. 1, the automatic tire inflation system may be used to controlair pressure in one or more of the tires 110 mounted to steer axle 114,drive axle 106 and trailer axles (not shown). The automatic tireinflation system may include one or more air hoses 112 in fluidcommunication with each tire 110. Other automatic tire inflationsystems, such as without limitation those disclosed in U.S. Pat. Nos.7,273,082, 6,325,124, and 6,105,645, and U.S. Pub. App. No.2009/0283190.

Now referring to FIGS. 16-17, a rotary union 652 may be provided forsupplying air from an air pressure supply 152 in an automatic tireinflation system through air hoses 604 to the rotating tires (not shown)mounted to wheels 108. A hub cap 606 may be provided at each end of thewheel spindle 154 for retaining lubricant in the wheel bearings (notshown). An air conduit 176 may supply air to the rotary union 652through an axial channel 302 in the wheel spindle 154. The rotary union652 may be supported and positioned in the center end of the wheelspindle 154, and may sealingly engage the interior of the wheel spindle154 if air is injected directly into the axial channel 302 of the wheelspindle 154.

As shown more particularly in FIG. 17, the rotary union 652 may have afirst stationary part 654 or stator having a passageway 656therethrough. The first stationary part 654 may include a filter 674 toremove debris that may be carried through the axial channel 302. Thepassageway 656 may be in fluid communication with the air pressuresupply 152 through air conduit 176 and, in some embodiments, a valveblock 252. A first rotary seal 658 may be supported in and encircle thepassageway 656. The rotary union 652 may include a rotatable partincluding a tubular member 660 having a first end 662 and a second end664. The second end 664 of the tubular member 660 may be coaxiallyextendable through and longitudinally and rotationally movable in thepassageway 656, and may sealably engage the first rotary seal 658 and soas to allow sealed fluid communication with the air pressure supply 152.The first end 662 of the tubular member 660 may be rotatably andsealably connected through a second rotary seal 668 to an air connection666 or tee-body mounted on the hub cap 606. The air connection 666 maybe provided on the hub cap 606 for communicating air to the tire ortires 110 (seen in FIG. 1) via an air hose 604 (seen in FIG. 16)connected to the wheel valves 602 (seen in FIG. 16). The first end 662of the tubular member 660 may include a shoulder 670 that co-acts with abearing 672. In operation, air may be supplied through the stationarypart of the rotary union 652. The hub cap 606 and air connection 666 mayrotate with the wheels 108 relative to the wheel spindle 154. Air mayflow from the pressure supply 152 through the filter 674 into thestationary part 654 of the rotary union 652. Air may flow from thestationary part 654 through the tubular member 660 to the tee-body 666.Air may flow from the tee-body 666 through air hoses 604 and tire valves602 into the tires. Of course, if the automatic tire inflation systemprovides for tire deflation, air may flow in the reverse direction asthat just described.

Thus, the automatic tire inflation system of FIGS. 16-19 may include anair pressure supply 152 and a suitable warning system comprising a flowswitch 172 and a warning system light 174, all of which may be used aspart of a high temperature warning system as disclosed herein. The useof a normally-closed valve 256 at a location near the wheel bearings 158and 178 or brake area on the wheel spindle 154 may provide a hightemperature warning system. Again, if the wheel spindle 154 reaches apredetermined temperature, the normally-closed valve 256 will open, suchas by the melting of a fusible plug 258 in some embodiments, releasingair from the air pressure supply 152 and actuating the warning systemlight 174 for notification of the operator. Of course, a warning buzzeror audible alarm may be used in place of the light 174. The operator mayquickly determine whether the warning system light 174 indicates apressure leak in the tires 110 or a high temperature problem in thewheel hub area. In some embodiments, air escaping through a channelformed in the valve 256 may provide an audible warning of hightemperature conditions. The valve 256 configuration may thus serve as awarning indicator. Thus, a warning light 174 need not be used, or may beused in conjunction with human-audible or ultrasonic warning indicators.

Referring now to the embodiment of FIG. 18, shown including an automatictire inflation system, additional normally-closed valves 256 may beprovided such as in the radial channel 352. The normally-closed valve256 may be connected to the air pressure supply 152 through the airconduit 176.

Referring now to FIG. 19, another embodiment is shown, which includes anautomatic tire inflation system, and further includes oneelectric-operated normally-closed valve 554 which, in this embodiment,is operable by two thermally electric switches 552 on the inner face 254of the wheel spindle 154. The electric-operated normally-closed valve554 may be located in a radial channel 352 so as to be adjacent theinner bearings 158 and/or outer bearings 178. Of course, the thermallyelectric switches may be placed at other suitable locations, such as onhubcap 606 or on stator 654.

Thus, a high-temperature warning system may be readily used inconnection with an automatic tire inflation system in a similar mannerand configuration as it would be used without an automatic tireinflation system. Any of the embodiments disclosed herein may be equallysuitable for implementation as standalone systems or in connection withan automatic tire inflation system.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the invention asdefined by the appended claims. Moreover, the scope of the presentapplication is not intended to be limited to the particular embodimentsof the process, machine, manufacture, composition, or matter, means,methods and steps described in the specification. As one will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized. Accordingly, the appended claims areintended to include within their scope such processes, machines,manufacture, compositions of matter, means, methods or steps.

What is claimed is:
 1. A high temperature warning system for asteer-axle wheel end assembly, the system comprising: a steer-axlespindle having an inner face and a free end; a pressurized fluid supply;a first normally-closed valve in sealed fluid communication with thepressurized fluid supply; a first heat sensitive control mounted to ornear the steer-axle wheel end assembly in a heat exchange relationshiptherewith, the first heat sensitive control being capable of opening thefirst normally-closed valve at a predetermined temperature; and awarning indicator connected to the pressurized fluid supply andactuatable upon opening of the first normally-closed valve.
 2. Thesystem of claim 1 wherein the first heat sensitive control is mounted tothe steer-axle spindle.
 3. The system of claim 1 wherein the first heatsensitive control is mounted to the inner face of the steer-axlespindle.
 4. The system of claim 1 wherein the first heat sensitivecontrol is mounted to the free end of the steer-axle spindle.
 5. Thesystem of claim 1 wherein the first heat sensitive control is mountednear the steer-axle spindle.
 6. The system of claim 1, furthercomprising: a valve block mounted to the inner face of the spindle in aheat exchange relationship therewith, the first normally-closed valvemounted to the valve block and the pressurized fluid supply sealinglyconnected to the valve block in fluid communication with thenormally-closed valve.
 7. The system of claim 6, wherein the first heatsensitive control is mounted to the inner face of the steer-axlespindle.
 8. The system of claim 6, wherein the first heat sensitivecontrol is mounted to the free end of the steer-axle spindle.
 9. Thesystem of claim 6, wherein the first heat sensitive control is mountedto the valve block.
 10. The system of claim 6, further comprising: thesteer-axle spindle forming a channel along the central axis of thesteer-axle spindle and in sealed fluid communication with thepressurized fluid supply at the inner face; and a second normally-closedvalve mounted to the steer-axle spindle in sealed fluid communicationwith the pressurized fluid supply through the channel.
 11. The system ofclaim 10, wherein the channel extends from the inner face to the freeend of the steer-axle spindle, the second normally-closed valve beingsealingly mounted to the channel at or near the free end of thesteer-axle spindle.
 12. The system of claim 10, wherein the channelextends from the inner face to an external surface of the steer-axlespindle, the second normally-closed valve being sealingly mounted to thechannel at the external surface of the steer-axle spindle.
 13. Thesystem of claim 10, wherein the first heat sensitive control is disposedin the channel.
 14. The system of claim 10, wherein the first heatsensitive control is mounted to the valve block.
 15. The system of claim10, further comprising: the first heat-sensitive control being capableof opening either or both of the first normally-closed valve and secondnormally-closed valve at a predetermined temperature, and the warningindicator actuatable upon opening either or both of the firstnormally-closed valve and second normally-closed valve.
 16. The systemof claim 10, further comprising a second heat sensitive control capableof opening the second normally-closed valve at a predeterminedtemperature.
 17. The system of claim 16, wherein the first heatsensitive control forms part of the first normally-closed valve and thesecond heat sensitive control forms part of the second normally-closedvalve.
 18. The system of claim 17 wherein the first heat sensitivecontrol comprises a eutectic alloy capable of melting and opening thefirst normally-closed valve upon reaching the predetermined temperature,and the second heat sensitive control comprises a eutectic alloy capableof melting and opening the second normally-closed valve upon reachingthe predetermined temperature.
 19. The system of claim 6, furthercomprising: the steer-axle spindle forming a channel along the centralaxis of the steer-axle spindle and extending from the inner face to thefree end of the steer-axle spindle, the channel being in sealed fluidcommunication with the pressurized fluid supply at the inner face, and arotary union sealingly mounted to the channel at the outer end of thesteer-axle spindle, the rotary union being in sealed communication withthe pressurized fluid supply and with a tire.
 20. The system of claim19, wherein the channel also extends from the inner face to an externalsurface of the steer-axle spindle, the system further comprising asecond normally-closed valve mounted to the steer-axle spindle in sealedfluid communication with the pressurized fluid supply through thechannel.
 21. The system of claim 20, wherein the first heat-sensitivecontrol is mounted to the inner face of the steer-axle spindle.
 22. Thesystem of claim 20, further comprising a second heat sensitive controlcapable of opening the second normally-closed valve at a predeterminedtemperature.
 23. The system of claim 22, wherein the secondheat-sensitive control is mounted to the inner face of the steer-axlespindle.
 24. The system of claim 22, wherein the first heat sensitivecontrol forms part of the first normally-closed valve and the secondheat sensitive control forms part of the second normally-closed valve.25. The system of claim 24, wherein the first heat sensitive controlcomprises a eutectic alloy capable of melting and opening the firstnormally-closed valve upon reaching the predetermined temperature, andthe second heat sensitive control comprises a eutectic alloy capable ofmelting and opening the second normally-closed valve upon reaching thepredetermined temperature.
 26. The system of claim 1, furthercomprising: the steer-axle spindle forming a channel along the centralaxis of the steer-axle spindle and in sealed fluid communication withthe pressurized fluid supply at the inner face, and the firstnormally-closed valve mounted to the steer-axle spindle in sealed fluidcommunication with the pressurized fluid supply through the channel. 27.The system of claim 26, wherein the channel extends from the inner faceto the free end of the steer-axle spindle, the first normally-closedvalve being sealingly mounted to the channel at or near the free end ofthe steer-axle spindle.
 28. The system of claim 26, wherein the channelextends from the inner face to an external surface of the steer-axlespindle, the first normally-closed valve being sealingly mounted to thechannel at or near the external surface of the steer-axle spindle. 29.The system of claim 26, wherein the first heat-sensitive control ismounted to the inner face of the steer-axle spindle.
 30. The system ofclaim 26, wherein the first heat-sensitive control is disposed in thechannel.
 31. The system of claim 26, wherein the first heat-sensitivecontrol is mounted to an external surface of the steer-axle spindle. 32.The system of claim 26, wherein the first heat sensitive control formspart of the first normally-closed valve.
 33. The system of claim 32,wherein the first heat sensitive control comprises a eutectic alloycapable of melting and opening the first normally-closed valve uponreaching the predetermined temperature.
 34. The system of claim 26,wherein the channel extends from the inner face to the free end of thesteer-axle spindle, the channel being in sealed fluid communication withthe pressurized fluid supply at the inner face, and wherein the channelalso extends from the inner face to an external surface of thesteer-axle spindle, the system further comprising: a secondnormally-closed valve mounted to the steer-axle spindle in sealed fluidcommunication with the pressurized fluid supply through the channel; anda rotary union sealingly mounted to the channel at outer end of thesteer-axle spindle, the rotary union being in sealed communication withthe pressurized fluid supply and with a tire.